The Northwestern University Transgenic and Targeted Mutagenesis (TTML) is a shared resource designed to produce genetically engineered mice for research projects of investigators of the Robert H Lurie Comprehensive Cancer Center (RHLCCC), Northwestern University's Feinberg School of Medicine (NUFSM), Evanston Northwestern Hospital (ENH) and Children's Memorial Research Center (CMRC). The transgenic laboratory was first organized at the CMRC in 1989 as part of the Markey Program in Developmental Biology, to provide a resource for generating transgenic mice by pronuclear microinjection. In 2003, the laboratory was moved to NUFSM under new leadership by Dr. Warren Tourtellotte and with substantial university support, including newly designed/renovated space and new equipment. Today, the facility has evolved into a highly utilized laboratory that provides a broad range of services to NU investigators, including generation of transgenic mice, gene targeting of embryonic stem (ES) cells, ES cell microinjection into blastocysts, cryopreservation and recovery of mouse embryos, and rederivation of pathogen free mouse strains. Since 2003, the TTML has been highly successful in reorganizing and expanding services, and has been highly successful in generating transgenic and targeted mutant mice. In 2005, services were expanded to offer embryo cryopreservation/recovery, rederivation and in vitro fertilization. The new services position NU and Cancer Center investigators to capitalize on emerging repositories of mutant mice generated around the world, most of which are stored as cryopreserved embryos. The TTML provides the necessary infrastructure to allow most investigators to access transgenic technology that normally requires expensive microinjection/tissue culture equipment and highly skilled staff with expertise in microinjection, microsurgeries, embryo manipulation, animal husbandry, and ES cell culture. TTML staff provide consultation on all aspects of transgenic related technologies ranging from animal protocol approval to breeding, screening and analysis of newly created transgenic or chimeric mice. Moreover, TTML staff are also available to provide guidance regarding targeting vector design, appropriate screening strategies, and DNA isolation methods for gene targeting projects. The TTML is governed by a faculty oversight committee which meets quarterly to provide guidance related to budgetary and operational issues. Over the last five years, Cancer Center investigators have become the primary group of NU investigators utilizing the TTML, emphasizing its pivotal role in the overall research mission of the RHLCCC.